Despite the fact that the sparse PCs from each condition are correlated, sparse PCA of the T2D condition alone still extracts several known T2D-linked genes (Fig 4E, bold): MPV17 [26], SMCO4 [27], DDIT3 [28,29], NFE2L2 [30], G6PC2##1 [31], and SPPL2A [32]. The gene discussed is SMCO4; the disease is type 2 diabetes mellitus.